Nickel sulfide titanium dioxide composite nanowires, preparation methods and applications

Abstract

This invention relates to the field of composite nanowire preparation technology, specifically to a nickel sulfide / titanium dioxide composite nanowire, its preparation method, and its application: Using nickel-titanium-based nanowires obtained by nickel ion exchange of Na2Ti3O7 nanowires as raw material, the nickel-titanium-based nanowires are mixed with sublimed sulfur and then subjected to a two-step heating process to prepare nickel sulfide / titanium dioxide composite nanowires. The nickel sulfide / titanium dioxide composite nanowires obtained by this technical solution have a regular morphology and uniform distribution of nickel sulfide and titanium dioxide, which can effectively enhance the adsorption of discharge intermediate products by the positive electrode carrier of lithium-sulfur batteries and accelerate their conversion, thereby improving the electrochemical performance of lithium-sulfur batteries. Furthermore, the process for preparing high specific surface area and highly active polar transition metal composite materials using this technical solution is simple and easy to produce.

Description

Technical Field

[0001] This invention relates to the field of composite nanowire preparation technology, and particularly to a nickel sulfide titanium dioxide composite nanowire, its preparation method, and its application. Background Technology

[0002] With the widespread use of portable electronic devices in daily life, the energy density of existing lithium-ion batteries is gradually reaching the limits of material properties, making it difficult to meet people's demand for high-energy-density energy storage materials. Lithium-sulfur batteries have advantages such as high theoretical energy density (2600Wh / Kg), abundant resources, and low price, and are considered to be a highly promising next-generation low-cost and high-efficiency energy storage and conversion system. However, lithium-sulfur batteries still have many problems. In particular, the intermediate products of lithium-sulfur battery charging and discharging (lithium polysulfides) are easily dissolved in the electrolyte, leading to the loss of active materials.

[0003] To address the issue of intermediate product dissolution, researchers have undertaken numerous attempts. Among these, the use of transition metal complexes as polar electrocatalysts has become the mainstream research approach. These complexes serve two main functions: first, since both transition metal complexes and lithium-sulfur battery intermediate products are polar materials, the transition metal complexes can effectively adsorb these intermediate products, thereby mitigating their dissolution into the electrolyte; second, transition metal complexes can accelerate the conversion of lithium polysulfides, thus reducing the persistence time of soluble intermediate products. Therefore, the preparation of high specific surface area and highly active polar transition metal complex materials through simple methods is urgently needed. Summary of the Invention

[0004] The purpose of this invention is to provide a nickel sulfide titanium dioxide composite nanowire, its preparation method, and its application, thereby solving the problem that existing methods for preparing high specific surface area and highly active polar transition metal composite materials are too complex.

[0005] To achieve the above objectives, the present invention provides a method for preparing nickel sulfide-titanium dioxide composite nanowires, the method comprising the following steps:

[0006] 2g of anatase phase titanium dioxide powder was mixed with 80mL of 10 mol / L sodium hydroxide solution and transferred to a high-pressure hydrothermal reactor for constant temperature reaction to obtain Na2Ti3O7 nanowires.

[0007] 1 g of the obtained Na2Ti3O7 nanowires were hydrothermally reacted with 80 mL of a 0.5 mol / L nickel acetate aqueous solution in an oven to obtain nickel-titanium based nanowires.

[0008] 1 g of the prepared nickel-titanium-based nanowires were mixed evenly with 1 g of sublimed sulfur and placed in a tube furnace under an argon atmosphere. The nickel sulfide / titanium dioxide composite nanowires were obtained by heating in two steps.

[0009] In the step of "mixing 2g of anatase phase titanium dioxide powder with 80mL of 10 mol / L sodium hydroxide solution and transferring it to a high-pressure hydrothermal reactor for constant temperature reaction to obtain Na2Ti3O7 nanowires", the constant temperature reaction temperature is 200℃ and the constant temperature reaction time is 24h.

[0010] In the step "taking 1 g of the obtained Na2Ti3O7 nanowires and reacting them with 80 mL of nickel acetate aqueous solution in an oven to obtain nickel-titanium based nanowires", the oven temperature is set to 60℃ and the hydrothermal reaction time is 12h.

[0011] In the step "After mixing 1 g of the prepared nickel-titanium-based nanowires with 1 g of sublimed sulfur evenly, place them in a tube furnace under an argon atmosphere, and obtain nickel sulfide / titanium dioxide composite nanowires through two-step heating", the two-step heating process is as follows:

[0012] The temperature range for the first step of heating is 100℃-160℃, and the temperature is maintained for 1 hour-20 hours.

[0013] The second step involves heating at a temperature range of 400℃-800℃ and holding the temperature for 10-200 minutes.

[0014] In the step "After mixing 1 g of the prepared nickel-titanium-based nanowires with 1 g of sublimed sulfur, place them in a tube furnace under an argon atmosphere, and obtain nickel sulfide / titanium dioxide composite nanowires by heating in two steps", the heating rate of the two steps is 1-10℃ / minute.

[0015] The present invention also provides a nickel sulfide titanium dioxide composite nanowire, which is prepared by the preparation method of nickel sulfide titanium dioxide composite nanowire as described above.

[0016] The present invention also provides a nickel sulfide titanium dioxide composite nanowire for use in composite cathode materials for lithium-sulfur batteries.

[0017] The specific preparation method of the composite cathode material is as follows:

[0018] Sublimed sulfur, nickel sulfide / titanium dioxide composite nanowires with a mass ratio of 80:16:4 were mixed uniformly with carbon nanotubes, and the mixture was heated to 155°C and held for 12 hours to obtain sulfur / nickel sulfide / titanium dioxide composite cathode material.

[0019] This invention discloses a nickel sulfide / titanium dioxide composite nanowire, its preparation method, and its application. Using nickel-titanium-based nanowires obtained by ion-exchange of Na₂Ti₃O₇ nanowires with nickel as raw material, the nickel-titanium-based nanowires are mixed with sublimed sulfur and then prepared through a two-step heating process to obtain nickel sulfide / titanium dioxide composite nanowires. The nickel sulfide / titanium dioxide composite nanowires obtained by this technical solution have a regular morphology and uniform distribution of nickel sulfide and titanium dioxide. This effectively enhances the adsorption of discharge intermediate products by the positive electrode carrier of lithium-sulfur batteries and accelerates their conversion, thereby improving the electrochemical performance of lithium-sulfur batteries. Furthermore, the process for preparing high specific surface area and highly active polar transition metal composite materials using this technical solution is simple and easy to produce. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a flowchart of the preparation method of nickel sulfide titanium dioxide composite nanowires provided by the present invention.

[0022] Figure 2 This is the XRD pattern of the nickel sulfide / titanium dioxide composite nanowires provided by the present invention.

[0023] Figure 3 This is a SEM image of the nickel sulfide / titanium dioxide composite nanowires provided by this invention.

[0024] Figure 4 The first charge-discharge curve of the nickel sulfide / titanium dioxide composite nanowires provided by this invention for use in lithium-sulfur batteries at a rate of 0.2C is shown.

[0025] Figure 5 The present invention provides a cycle stability curve of nickel sulfide / titanium dioxide composite nanowires for lithium-sulfur batteries at a rate of 0.2C. Detailed Implementation

[0026] The following describes embodiments of the present invention in detail, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and are not to be construed as limiting the present invention.

[0027] Please see Figures 1 to 5This invention provides a method for preparing nickel sulfide-titanium dioxide composite nanowires, the method comprising the following steps:

[0028] S1: Take 2g of anatase phase titanium dioxide powder and mix it with 80mL of 10 mol / L sodium hydroxide solution, and transfer it to a high-pressure hydrothermal reactor for constant temperature reaction to obtain Na2Ti3O7 nanowires.

[0029] S2: Take 1 g of the obtained Na2Ti3O7 nanowires and react them with 80 mL of 0.5 mol / L nickel acetate aqueous solution in an oven to obtain nickel-titanium based nanowires;

[0030] S3: Take 1 g of the prepared nickel-titanium-based nanowires and mix them evenly with 1 g of sublimed sulfur. Place them in a tube furnace under an argon atmosphere and obtain nickel sulfide / titanium dioxide composite nanowires through two-step heating.

[0031] In this embodiment, nickel-titanium-based nanowires obtained by nickel ion exchange of Na2Ti3O7 nanowires are used as raw materials. These nickel-titanium-based nanowires are mixed with sublimed sulfur and then prepared through a two-step heating process to obtain nickel sulfide / titanium dioxide composite nanowires. The nickel sulfide / titanium dioxide composite nanowires obtained by this technical solution have a regular morphology and uniform distribution of nickel sulfide and titanium dioxide. This can effectively enhance the adsorption of discharge intermediate products by the positive electrode carrier of lithium-sulfur batteries and accelerate their conversion, thereby improving the electrochemical performance of lithium-sulfur batteries. At the same time, the process of preparing high specific surface area and high activity polar transition metal composite materials by this technical solution is simple and easy to produce.

[0032] Furthermore, in step S1, the isothermal reaction temperature is 200°C, and the isothermal reaction time is 24 hours.

[0033] Furthermore, in step S2, the oven temperature is set to 60°C, and the hydrothermal reaction time is 12 hours.

[0034] Furthermore, in step S3, during the two-step heating process:

[0035] The temperature range for the first step of heating is 100℃-160℃, and the temperature is maintained for 1 hour-20 hours.

[0036] The second step involves heating at a temperature range of 400℃-800℃ and holding the temperature for 10-200 minutes.

[0037] Furthermore, the heating rate in the two-step heating process is 1-10℃ / minute.

[0038] The present invention also provides a nickel sulfide titanium dioxide composite nanowire, which is prepared by the preparation method of nickel sulfide titanium dioxide composite nanowire as described above.

[0039] The present invention also provides a nickel sulfide titanium dioxide composite nanowire for use in composite cathode materials for lithium-sulfur batteries.

[0040] The specific preparation method of the composite cathode material is as follows:

[0041] Sublimed sulfur, nickel sulfide / titanium dioxide composite nanowires with a mass ratio of 80:16:4 were mixed uniformly with commercial carbon nanotubes, and the mixture was heated to 155°C and held for 12 hours to obtain sulfur / nickel sulfide / titanium dioxide composite cathode material.

[0042] Furthermore, the obtained sulfur / nickel sulfide / titanium dioxide composite cathode material was dispersed in NMP solvent with conductive carbon (Super P), conductive carbon (VGCF), and binder (PVDF) at a mass ratio of 7:1:1:1 to form a uniform slurry. This slurry was then coated onto aluminum foil and dried to obtain the lithium-sulfur battery cathode. Under an argon atmosphere, it was assembled into a 2035 coin cell for electrochemical performance testing. The anode was a lithium metal sheet, and the electrolyte consisted of 1 mol / L LiTFSI and 2 wt% LiNO3 dissolved in a DOL / DME mixed solution.

[0043] The above description discloses only one preferred embodiment of the present invention, and should not be construed as limiting the scope of the present invention. Those skilled in the art will understand that all or part of the processes of the above embodiments can be implemented, and equivalent changes made in accordance with the claims of the present invention are still within the scope of the invention.

Claims

1. A method for preparing nickel sulfide / titanium dioxide composite nanowires, characterized in that, Includes the following steps: 2g of anatase phase titanium dioxide powder was mixed with 80mL of 10 mol / L sodium hydroxide solution and transferred to a high-pressure hydrothermal reactor for constant temperature reaction to obtain Na2Ti3O7 nanowires. 1 g of the obtained Na2Ti3O7 nanowires were hydrothermally reacted with 80 mL of a 0.5 mol / L nickel acetate aqueous solution in an oven to obtain nickel-titanium based nanowires. 1 g of the prepared nickel-titanium-based nanowires were mixed evenly with 1 g of sublimed sulfur and placed in a tube furnace under an argon atmosphere. The nickel sulfide / titanium dioxide composite nanowires were obtained by heating in two steps. The two-step heating process is as follows: The temperature range for the first step of heating is 100℃-160℃, and the temperature is maintained for 1 hour-20 hours. The second step involves heating at a temperature range of 400℃-800℃ and holding the temperature for 10-200 minutes.

2. The method for preparing nickel sulfide / titanium dioxide composite nanowires as described in claim 1, characterized in that, In the step "2g of anatase phase titanium dioxide powder is mixed with 80mL of 10 mol / L sodium hydroxide solution and transferred to a high-pressure hydrothermal reactor for constant temperature reaction to obtain Na2Ti3O7 nanowires", the constant temperature reaction temperature is 200℃ and the constant temperature reaction time is 24h.

3. The method for preparing nickel sulfide / titanium dioxide composite nanowires as described in claim 2, characterized in that, In the step "1 g of the obtained Na2Ti3O7 nanowires were hydrothermally reacted with 80 mL of nickel acetate aqueous solution in an oven to obtain nickel-titanium-based nanowires", the oven temperature was set to 60℃ and the hydrothermal reaction time was 12 h.

4. The method for preparing nickel sulfide / titanium dioxide composite nanowires as described in claim 3, characterized in that, In the step "After mixing 1 g of the prepared nickel-titanium-based nanowires with 1 g of sublimed sulfur, place them in a tube furnace under an argon atmosphere, and obtain nickel sulfide / titanium dioxide composite nanowires by heating in two steps", the heating rate of the two steps is 1-10℃ / minute.

5. A nickel sulfide / titanium dioxide composite nanowire, characterized in that, It was prepared using the preparation method of nickel sulfide / titanium dioxide composite nanowires as described in claim 4.

6. A nickel sulfide / titanium dioxide composite nanowire as described in claim 5, characterized in that, Composite cathode materials used in lithium-sulfur batteries The specific preparation method of the composite cathode material is as follows: Sublimed sulfur, nickel sulfide / titanium dioxide composite nanowires with a mass ratio of 80:16:4 were mixed uniformly with carbon nanotubes, and the mixture was heated to 155°C and held for 12 hours to obtain sulfur / nickel sulfide / titanium dioxide composite cathode material.

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